Pipe slip insert



y 1951 A. T. BOATRIGHT 2,552,618

PIPE SLIP INSERT Filed March 18, 1947 2 Sheets-Sheet 2 Patented May 15, 1951 PIPE SLIP INSERT Arthur T. Boatright, South Gate, Calif., assignor to Textool Products 00., Inc., Vernon, Calif., a corporation of California Application March 18, 1947, Serial No. 735,410

4 Claims. (Cl. 24-263) This invention relates to improvements in drill pipe slips used in the handling of drilling tool strings incident to the lowering or raising of such strings into or out of a well casing. The slip is a device which engages the rotary table at the top of the casing and which by a wedging or other clamping action operates to engage and hold the drill string suspended while sections of drill pipe are added or removed as the drill string is lowered or raised.

One of the most common forms of drill pipe slips in current general use is of the general type shown in United States Letters Patent No. 2,119,- 731 comprising two or more hingedly articulated body members, the outer faces of said members being shaped to form portions of an inverted frusto-conical surface, the axis of which is substantially coincident with the axis of the drill string. The inner faces of the body members form a cylinder through which the drill pipe passes and are provided with one or more series of vertically disposed, overlapping counterbores in which are located a series of disc-like inserts having pipe-engaging teeth adapted to grip the drill pipe by reason of the wedging engagement of the inclined outer face of the body members with the rotary table. The inserts are provided with integral shanks disposed centrally thereof and extending through holes in the sidewalls of the body members to the outer faces thereof where they are engaged by a suitable locking means usually in the form of a rod extending through holes in the shank elements of one group or series of inserts. The holes through which the shanks of the inserts in each series extend are spaced closer together than the diameters of the discs and the discs are therefore formed with abutting, flattened sides to resist any tendency to turn. These flattened sides are equidistant from the center of the disc and in the replacement of worn or dull inserts it is possible to place one or more inserts in an inverted position, resulting in such insert presenting to the pipe, teeth so disposed as to eilect a decided reduction in the gripping efficiency of that insert and an increased risk of dropping the entire string. Recently, to overcome this danger at least in part, inserts have been provided with pyramid-shaped teeth so that regardless of how the insert may be applied, the same type of angle will be presented, although it is less efficient than the angle of a properly applied insert of the earlier type.

With the foregoing considerations in mind, it is an object of the present invention to provide a drill slip insert usable in a conventional .form of drill slip body member which insert is so con-' structed that it cannot be placed in an inverted position.

Another object of the invention is to provide a drill slip insert having the pipe-engaging teeth thereof disposed in staggered relation to each other for more efficient resistance to any tendency of the drill pipe to slip or to turn.

Still another object of the invention is to provide a drill pipe slip insert which is so constructed that upon any tendency of a drill pipe gripped thereby to turn, incident to the adding or removal of other sections of drill pipe, the insert will tend to turn about its own axis with consequent tighter engagement with the drill pipe.

A still. further object of the invention is to provide a drill pipe insert having a periphery so shaped that the adjacent faces of adjacent inserts are disposed in close proximity to each other while at the same time permitting a slight amount of individual rotation whereby each insert is enabled to accommodate itself to such irregularities in the surface of the drill pipe as develop in normal usage.

Still another object of the invention is to provide a drill pipe slip insert in which at least one diameter of the pipe-engaging surface extends between points on the periphery of the surface which are disposed at different distances from the axis of the shank associated with the insert.

Still another object of the invention is to provide a drill pipe insert construction in which the teeth are formed as rights and lefts so that when a series of inserts are installed in a slip body in alternation, the tendency of the drill pipe to turn will be more efi'iciently resisted.

With the foregoing objects in view, together with such other objects and advantages as may subsequently appear, the invention resides in the parts and in the combination, construction and' arrangement of parts hereinafter described and claimed and illustrated by way of example'in the accompanying drawings, in which:

Fig. 1 is a top plan view of a drill pipe slip in member supplied with pipe-gripping inserts of the present invention,

Fig. 4 is a side elevation of an insert embodying the principles of the invention,

Fig. 5 is a fragmentary, enlarged view of the body members I, 2 and 3 which are hinged to=- gether at 4 and 5 and which are provided= with--.

handle portions 6, l and 8 secured thereto by suitable bolts 9.

drill pipe. bers are inclined upwardly and outwardly to form portions of an inverted frusto-conical surfacey which portions engage the upper end of a main bushings! l associ'atedi with ttl'iet rotary table con structiorr l2; faces are provided with hardened steel inserts [3 adapted to? engage a drill pipe and T tOibe pressed -irite tight? engagementtherewith xby the wedging ='action: effectediby. thezengagement of the outer .inclinedifacessm lWithIthe main bushing {I lunder the influence 'ofcthecweig'ht' of the toolstring "which:mayb'e :iseveral tons; In: the most commonzformzizof .slipi body members in. current:

general use,: the .l inner face thereof is provided; with one: or more: SSIiGSr' of vertically: disposed;-

coimterboresilewhich are-located closer together:

thantthe diameter Jof the'icounterb'ores; whereforetheyiintersect to :form'. airelatively' wide, shallow. channel l'i5; .the sidewalls of whichare i'nzithe form ofiar series ofvpairs ofopposed segments of circles; Extendingith'rough thewall of the body;

member to' thertoutertface thereof at the center of "eachfcounterbore is a holeclslithrough' whichthe shank 1 l 1 of" the" insert 'exten'dszz noted from Fig. 1 that'the series.- orsets of couri terbore's' and. the holesrlii are radially disposed about the axis of the dril'lpipfevD so :that'th'e" gripping rpressure ofthe'inserts isexerted in directions normal to"and intersecting said axis. Atits outer-end; each insert shank is provided w-itha vertically disposed; transverse hole Isa-and: arrod 19* extends; through. these holesiin each vertically disposed seriesoi shanks to hold the insertsiin assembly'witlf the body member, Any

suitable means may beused to. secure the rod manplace; as by forming I the rod with an eye. portion 2.0 through which: a. screw 21 extends andi'isf. threaded into the body "member; Thus this single screw' serves to hold an entire seri'esi ofsinserts inf. place, facilitating: the replacement OfiiIlSErtS? a's :isi-ifrequently' necessary; All of the foregoing construction isi-know-niirr th'eertand; the present invention i is particularly *directed to improvements .thereover whichiwill: now "beispeicific'ally described;

Heretofore, the-.insertst employed: inibody memihers-cf the; type described have beerrformedwith abutting flattened 3 sides disposed:- at the points. of-' intersection of? adjacent counterbores; Fur.-

ther to acccommodate this constructi'om' the:

bottom" counterbore of each series was formed with fiat sidewall to engage the lower'flat side':

of-lthe lowermost insert of-each series of inserts.

Since-i the inserts wereformed' with :parallel', ,fiat:

sides equidistant from the axis of the: shank", they couldbeplaced in the body member in inverted position With: disadvantages that have:

been mentioned. Also, sin'cexthese'flat sideswere The inner 1 faces of the body members are curved and unite-to'form a circular: outline of somewhat greater diameter than the" The outer faces Hiot the body meml- Thec'ibody members at their inner:

It will be:

of considerable length and were held in abutting relation, rotation of the inserts was effectually prevented.

In normal use, the ends of drill pipe sections become worn or acquire scores or other irregularities from frequent engagement with slips or wrenches incident to the adding or removal of sections: If thez' insert is permitted to rotate slightly; about the axis of its shank, it is enabled to accommodate itself to such conditions and to engage the pipe at the sides of the insert,

sincethe efiect of such rotation is to, in effect, adapt the pipe-engaging face of the insert to a slightly:lesser' diameter of pipe. To this end it will benoted that the hole IS in the insert shanks is made sl-igh'tlywider as at 22 so that this movement. may, take. place without sacrificing the closer fit of the rodIS in the holes in the direction -of the axis of the shank.

The pipe-engaging face of each insert is circular in form:and-.-is-:-ofsuch diameter as to fit Within. one of the: counterbores. Each insert at-its lower .edgeiscut away as at 23-to receive the upper face of the. insert immediately below and this-'cut-aWay-portion is given a somewhat larger radius than the radius of the insert fitting therein to provide clearance whereby the inserts' may each partake. of limited rotativemovements about. axes of-thecounterbores, the projection of the lower insert-intothe cut-away portion-of theaupper insert servingasa stop-to limit theextent-of movement of the upper insert. The points 24,-. 2 3-: atieachisidezofthe-:cut-away. portion. of-each. insert are. disposed. near the; points. of intersection of. adj acentcounterhores and thus in the case-'ofthe.lowermostinsert of each. vertically disposed series; these points will engage the flat sidewall .of' the lowermost counterbore A inieach. series andwill be. prevented from. turning; and v .by the." interengagement' previously described,- each insert will-. -prevent.. the. insert above it. from more than the limited rotative. movement provided for. Further, since the: lowermostinsert of each series orgroup can be placed inits counterbore in .only one position-,. it follows that all: of the other inserts in. the group can .-.be inserted only in a corresponding, position, makingit impossible toplace any insert in. the bodymember in' an inverted position-s The toothed pipe-engaging-faee' of each insert'is curved to-fit thesize-of drillpipefor which it is intended as best shown in Figs. 1' and 6.- Theteeth-are formed by cutting, aSeriesof grooves 25 -transverselyj ofthe: face of the insert, the.

L grooves-beingrso:spaced and Of'fSllCh depth as to produce-r aseries: of sharp edges having" the. desiredradius: to accommodate :the -drill pipe. An economical manner of: cutting these grooves is toplace a number of inserts in .a circle in a suitable. fixture and to-xcut' a: thread having a minor. di.'-' ameter'. equal. to:the diameter: ofgthe drill .pipe' in the: faces. of the. inserts.;: 'Ihisprcduces grooves which have: a: slight inclination: with respect to: the. horizontal; as most clearly shown in: Figs. 3: fan-d5. Alternatively, the grooves. :may be: milledrin so. as: to. produce :a horizontal I tooth face as" shown rin Fig: '7, or 'ifanextreme: angle isdesired; a double'or: triple thread may: be' cut in the mannerdescribedrabove. Following the cuttingwof the teeth-many suitable. manner, the teeth are-notchedas at 2'7", thenotchespreferably bei-n-gstaggered so that a. 'considerable vertical' space will exist" between at least a portion of feach tooth and the next tooth vertically above it. Also, desired the inserts: may be. formed:

as rights and lefts either by cutting the grooves as right and left hand threads or by the arrangement of the notches 27 or both as may be found most expedient.

While the slip is holding the drill string suspended incident to the addition or removal of sections of drill pipe, the slip must frequently resist the turning movement the pipe. The cut-away portion at the under side of the insert in addition to its rotatioznpreventing function possesses another advantage in that since its upper edge is farther away from the axial line of the shank than the lower edge, any tendency of the drill pipe to turn will cause each insert also to tend to turn about its axis with resultant tighter engagement of the drill pipe by the side portions of the inserts, an action which cannot be obtained when the pipe-engaging area of the insert is uniformly disposed about the axis of its shank as has been the practice heretofore.

Thus it is that there has been created an insert for drill pipe slips which may be installed in existing slip body structures which cannot be wrongly placed therein and which therefore may be provided with the most efficient form of pipeengaging teeth. Further, by the improved construction, each insert is free to adjust itself to the surface conditions of the drill pipe. Still further, any tendency of the drill pipe to turn is resisted by the creation of a tighter engagement with the slip.

While I have shown and described a specific embodiment of my invention, I do not limit myself to the exact details of construction set forth, and the invention embraces such changes, modifications and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

In the foregoing specification, the invention has been described in connection with drill pipe slips and it will be of great value for that purpose. It is not intended by such description, however, to limit the invention to that use since the principles may be used with equal advantage in tubing and easing slips or other places where it is desired to hold a pipe by a series of removable inserts so mounted as to have capacity for independent accommodation to the surface of the pipe, tube or casing engaged thereby.

I claim:

1. The combination with a drill pipe slip body member having on the inner face thereof a shallow, vertically disposed channel formed by a series of overlapping counterbores, of a series of pipe-engaging inserts loosely secured to said body member and disposed one in each of said counterbores; each of said inserts comprising a shank portion mounted in said body member and an integrally formed pipe-engaging portion in the form of a disc axially aligned with said shank and seated in one of said counterbores; said disc having an end face provided with pipe-engaging teeth projecting beyond said inner face and being curved to conform to the surface of a drill pipe to be engaged thereby, said disc portion further having at one point on its periphery a concave recess into which the convex edge portion of an adjacent insert may extend; the engage ment between said recess and said convex edge serving to permit limited, independent, rotative movements of said inserts.

2. As an article of manufacture, a pipe-engag ing insert for use in drill pipe slips, said insert comprising a cylindrical shank portion and an integral pipe-engaging portion in the form of a disc axially aligned with said shank, said pipeengaging portion having an end face provided with pipe-en aging teeth arranged to conform to the periphery of a drill pipe to be engaged thereby and having an edge thereof provided with a concave recess into which the edge portion of another insert may extend to limit the extent of rotative movement of said insert.

3. The combination with a pipe slip body member having on the inner face thereof a vertically disposed channel, of a series of pipe-engaging inserts disposed in said channel and having shanks mounted in and extending through said body member with capacity for limited rotative movement about the axes of said shanks, and means for securing said inserts in said body member comprising a vertically disposed hole in each of said shanks and a rod extending through all of said holes; said holes being wider transversely of the axes of said shanks than parallel thereto to permit said limited rotative movement while preventing endwise movement of said shanks relative to said rod.

4. The combination with a drill pipe slip body member having on the inner face thereof a shallow, vertically disposed channel formed by a series of overlapping counterbores, of a series of pipe-engaging inserts loosely secured to said body member and disposed one in each of said counterbores; each of said inserts comprising a shank portion mounted in said body member and an integrally formed pipe-engaging portion in the form of a disc axially aligned with said shank and seated in one of said counterbores; said disc having an end face provided with pipe-engaging teeth projecting beyond said inner face and being curved to conform to the surface of a drill pipe to be engaged thereby; said disc portion further having at one point in its periphery a concave recess into which the convex edge portion of an adjacent insert may extend; the engagements between the said recesses and convex edges of said inserts being effective to prevent inverted installation of any insert in the series.

ARTHUR T. BOATRIGHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,234,041 Knapp July 17, 1917 1,560,701 Layton Nov, 10, 1925 1,849,216 Adair Mar. 15, 1932 2,012,337 Burns Aug. 27, 1935 2,119,731 Abegg June 7, 1938 2,287,432 Kinzbach June 23, 1942 

